The present invention generally relates to a door latch device. In particular, the invention relates to structures and methods for a door latch device used with a panic device for doors wherein the locking as well as the unlocking of the door can be controlled by the door latch device.
Panic devices for doors have been in use in buildings for approximately 100 years and provide a useful means for allowing unrestricted escape from the building in situations such as an emergency, while providing a reasonable amount of security against unauthorized access. Panic devices are generally used on single action outward opening doors and provide retention within the door frame either into the threshold, transom or door frame to hold the door in the closed position when not in use.
There are numerous types and styles of mechanisms used for operating the panic devices where bolts reciprocate vertically in and out of the door frame and extend from the top and bottom of the door. Most of these mechanisms include or are adapted to include a panic bar release arrangement on the inside of the door for rapid and foolproof actuation of the bolts by merely depressing the panic bar to open the door. Many of such mechanisms include an often desirable feature of permitting manipulation of the panic device to latch the bolts in a retracted position during business hours or the like, whereby the door is free to swing open without operating the panic bar or hitting any other release mechanism.
To provide operation of installations of this type, some form of bolt latching mechanism is usually provided which retains the bolts in the retracted position when the interior or exterior actuating device is operated during the time the door is open. This prevents the need to continue pressure on the panic bar or key in order to prevent the bolt from contacting the ground or door frame while the door is swinging during the open and closed cycles.
A problem with these types of mechanisms, however, is that these mechanisms use a keeper plate or trip mounted on the door frame which is an added component to the door assembly. Thus, the added component increases the assembly required to install the door, resulting in higher installation costs. Further, the added component increases the chance for the component to fail, resulting in costly repairs, inefficient use of work space, and unsafe conditions. Further, the bolts in these mechanisms commonly fail to remain in the retracted position when the door has been opened, resulting in damage to the frame or threshold since the bolt strikes the frame or threshold upon closing.
A need, therefore, exists to safely and clearly open a door with a panic device. The solution, however, must be able to retain the bolting mechanism in the retracted position until the door has completely closed. Further, the solution must be capable of sensing that the door has closed to extend the bolt after the door has completely closed.
An example of a current panic device wherein the bolts may be retracted is a key operated lock which also services to lock the bolts in the retracted position. By depressing a panic bar, as described in the United States patent to T. Bejarano, U.S. Pat. No. 3,334,500 the bolts may be retracted. Other examples of such devices wherein the bolts may be retracted by a panic device are described in U.S. Pat. No. 3,993,335 to Schmidt, U.S. Pat. No. 3,940,886 to Ellingson, Jr., and U.S. Pat. No. 4,839,988 to Betts et. al.
Currently, other panic devices use Pullman latches which rotate about a horizontal axis and use a spring loaded mechanism. These panic devices usually consist of a mechanical system concealed within the vertical lock stile of the door connected with a surface mounted actuating push bar or pad mounted horizontally across the inside face of the door. The two parts of the system are normally linked mechanically. The mechanism within the door stile operates a latch or bolt system which retains the door in the closed position. In this system, the latch or bolt is retained in a keeper plate which is mounted on the door frame.
These mechanisms also do not solve the current need since the bolts often do not stay in the retracted position and drag along the ground or across the door frame. Further it is often the case that the door mounted components are installed by the door manufacture in the door assembly and the frame components such as keeper plates are sent to the site separately to be installed after the door frame has been erected. Frequently, the frame mounted components go astray and often the components are installed with less accuracy than can be achieved in the factory. This can lead to potentially dangerous situations should the device fail to open in an emergency.
The present invention provides an improved latching device that can keep the latch assembly in the disengaged position until after the door has closed. This leads to improved safety and maintenance on the door and door frame. The present invention can also be used without keeper plates and does not require a separate trip device mounted to the frame. This leads to installation cost reductions and improved safety for the occupants of the building.
Thus, there is provided by the invention disclosed herein an improved door latch device which overcomes many of the inadequacies of door latches known to the prior art. The invention provides for the mounting of a novel door latch device on the internal side of the door for providing a latch assembly which, rather than vertically extending from the door to engage the door frame, rotatably engages and disengages the door frame. This door latch device, upon mechanical instructions from the actuation of the panic exit device, or other device such as a key lock, is rotated into a disengaging and engaging position, respectively, to allow the door to be opened and to be closed.
In an embodiment, the door latch device comprises at least one housing fixed within the door stile and at least one fork positioned inward of the housing and slidably engaged to the housing. The door latch device further comprises a latch assembly rotatably mounted to the housing and mechanically connected to the fork. The latch assembly is rotatable from an engaged position in a first rotational direction to a disengaged position to allow the door to open. The latch assembly also is rotatable from the disengaged position to the engaged position in a second rotational direction to engage the door frame after the door has closed.
In an embodiment, the latch assembly comprises a latch rotatably connected to the housing. Additionally, a pair of linkages are positioned below the latch and rotatably connected to the housing. A pair of connecting rods are positioned between the latch and the pair of linkages and are slidably engaged to the pair of linkages. Further, a bias member is fixed to the pair of connecting rods and to the fork. The latch assembly further comprises a rocker element positioned between the housing and the latch wherein the rocker element is rotatably connected to the housing and slidably engaged within the latch.
The pair of linkages have a linkage pin positioned in the middle of the linkages while the connecting rods each have a rod slot for receiving the linkage pin.
The latch has a projection facing the door stile in the engaged position and rotated downward ninety degrees in the disengaged position. The latch further has a latch aperture positioned opposite the projection wherein the latch aperture is rotatably connected to the housing. The rocker element has a rocker pin positioned to mechanically connect to the projection during the second rotational direction. The rocker element further has a bridge positioned within the door stile in the engaged position and positioned outside the door stile in the disengaged position.
The present invention further provides a method of engaging and disengaging a door latch device for a door fitted in a door frame comprised of activating the fork in a downward direction. Thereupon, the latch assembly is rotated from an engaged position in the first rotational direction to a disengaged position to disengage from the door frame. A lost motion arrangement, preferably in the form of slot and pin connections between the housing and the fork permit the latch to be captured in an over center position and held against returning to the latched position while the door remains open. The method also provides for sensing the door frame by the latching mechanism upon the closing of the door. Further, the latch is rotated from the disengaged position to the engaged position in a second rotational direction to engage the door frame after the door frame has been sensed.
An advantage of the present invention is to provide a door latch device that efficiently retains and releases a door.
Another advantage of the present invention is to provide a latch assembly that moves from an engaged position to a disengaged position when the door is opened.
Another advantage provided by the present invention is the automatic sensing of the door frame during a closing movement of the door.
Another advantage of the present invention is to provide a latch assembly that automatically moves from the disengaged position to the engaged position when the door frame is sensed.
Another advantage is to provide a lost motion effect to prevent the latch from returning to the latched position while the door is open.
Another advantage of the present invention is to provide a door latch device eliminating a striker plate and/or a trip mechanism mounted to the door or frame.